US 6880967 B2 Abstract A temperature of an electrolytic capacitor
24 incorporated in equipment is detected, a remaining lifetime in actual use is calculated based on a temperature-lifetime law, and the remaining lifetime is indicated. A thin film tape 23 is wound around a temperature sensor 22 for insulation, and the electrolytic capacitor 24 and the temperature sensor 22 are accommodated in a heat-shrinkable tube 25, the secondary temperature sensor 22 is brought into tight contact with the primary electrolytic capacitor 24. Claims(26) 1. An estimating method of a remaining lifetime of a subject, comprising:
calculating the remaining lifetime at a predetermined temperature in accordance with an arithmetic expression based on a temperature-lifetime law, and
converting the calculated remaining lifetime into a remaining lifetime in actual use.
2. The estimating method of a remaining lifetime according to
said calculating step and said converting step are carried out whenever a predetermined time is elapsed,
in said calculating step, said predetermined time elapse in actual use is converted into an elapsed time at said predetermined temperature, and the converted value is subtracted from the remaining lifetime, and
said converting step is carried out based on a proportional relation between the remaining lifetime at said predetermined temperature and the remaining lifetime in actual use.
3. The estimating method of a remaining lifetime according to
in said calculating step, said conversion is carried out based on the temperature-lifetime law using a temperature at the time of actual use, and
in said conversion step, the calculated remaining lifetime is converted into the remaining lifetime in actual use based on a remaining lifetime at another time point at said predetermined temperature and an elapsed time in actual use corresponding to said other time point while using a total remaining lifetime at the initial stage at said predetermined temperature as a reference.
4. The estimating method of a remaining lifetime according to
5. A structure for detecting a temperature of a capacitor wherein an insulating tape is wound around a temperature sensor which detects a temperature of said capacitor to bring said temperature sensor into tight contact with said capacitor.
6. A structure for detecting a temperature according to
7. A structure for detecting temperature according to
8. An electronic equipment having a capacitor, comprising:
a temperature sensor for detecting a temperature of said capacitor,
calculating means for calculating a remaining lifetime of said capacitor using a detected temperature from said temperature sensor,
converting means for converting the calculated remaining lifetime into a remaining lifetime in actual use, and
informing means for informing of the calculated remaining lifetime, wherein
said calculating means includes a calculating section for calculating the remaining lifetime at a predetermined temperature in accordance with an arithmetic expression based on a capacitor temperature-lifetime law.
9. The electronic equipment according to
said calculating means calculates the remaining lifetime of said capacitor in actual use,
said converting means includes a converting section for converting the remaining lifetime at the predetermined temperature calculated by said calculating section into the remaining lifetime in actual use, and
said informing means indicates the calculated remaining lifetime.
10. The electronic equipment according to
said calculating means calculates the remaining lifetime of said capacitor in actual use whenever a predetermined time is elapsed,
said calculating section converts said predetermined time elapse in actual use into an elapsed time at said predetermined temperature and subtracts the converted value from the remaining lifetime, and
said converting section converts based on a proportional relation between the remaining lifetime at said predetermined temperature and the remaining lifetime in actual use.
11. The electronic equipment according to
said calculating section carries out said conversion based on a capacitor temperature-lifetime law using a detected temperature from said temperature sensor, and
said conversion section converts the calculated remaining lifetime into the remaining lifetime in actual use based on a remaining lifetime at another time point at said predetermined temperature and an elapsed time in actual use corresponding to said other time point while using a total remaining lifetime at the initial stage at said predetermined temperature as a reference.
12. The electronic equipment according to
13. The electronic equipment according to
14. The electronic equipment according to
said temperature sensor around which said insulting tape is wound and said capacitor are accommodated in a heat-shrinkable tube and are integrally formed together, and
said temperature sensor is connected to said calculating means through a lead wire.
15. The electronic equipment according to
16. The electronic equipment according to
said calculating means includes a deterioration degree calculating section for calculating a rate of the remaining lifetime at the predetermined temperature calculated by said calculating section to the initial total remaining lifetime at said predetermined temperature, and
said informing means indicate said calculated deterioration degree.
17. The estimating method of a remaining lifetime according to
18. The estimating method of a remaining lifetime according to
19. The estimating method of a remaining lifetime according to
20. An electronic equipment having capacitor, comprising:
a temperature sensor for detecting a temperature of said capacitor,
a circuit arrangement which calculates the remaining lifetime of said capacitor using a detected temperature from said temperature sensor,
a circuit arrangement which converts the calculated remaining lifetime into a remaining lifetime in actual use, and
a circuit arrangement which informs the calculated remaining lifetime, wherein
said circuit arrangement which calculates the remaining life time includes a calculating section for calculating the remaining lifetime at a predetermined temperature in accordance with an arithmetic expression based on a capacitor temperature-lifetime law.
21. The electronic equipment according to
said circuit arrangement for calculating the remaining life time calculates the remaining lifetime of said capacitor in actual use, and
said circuit arrangement which converts the calculated remaining lifetime includes a converting section for converting the remaining lifetime at the predetermined temperature calculated by said calculating section into the remaining lifetime in actual use.
22. The electronic equipment according to
said circuit arrangement for calculating the remaining life time calculates the remaining lifetime of said capacitor in actual use whenever a predetermined time is elapsed,
said calculating section converts said predetermined time elapse in actual use into an elapsed time at said predetermined temperature and subtracts the converted value from the remaining lifetime, and
said converting section converts based on a proportional relation between the remaining lifetime at said predetermined temperature and the remaining lifetime in actual use.
23. The electronic equipment according to
said calculating section carries out said conversion based on a capacitor temperature-lifetime law using a detected temperature from said temperature sensor, and
said conversion section converts the calculated remaining lifetime into the remaining lifetime in actual use based on a remaining lifetime at another time point at said predetermined temperature and an elapsed time in actual use corresponding to said other time point while using a total remaining lifetime at the initial stage at said predetermined temperature as a reference.
24. The electronic equipment according to
25. The electronic equipment according to
26. The electronic equipment according to
said circuit arrangement which calculates the remaining lifetime includes a deterioration degree calculating section for calculating a rate of the remaining lifetime at the predetermined temperature calculated by said calculating section to the initial total remaining lifetime at said predetermined temperature, and
said circuit arrangement which informs the calculated remaining lifetime indicates said calculated deterioration degree.
Description 1. Field of the Invention The present invention relates to a method for estimating a remaining lifetime of a capacitor and the like, a temperature detecting structure suitable for the method, and various electronic equipment such as a power supply unit having such a capacitor. 2. Description of the Background Art In electronic equipment of this kind, for example, a power supply unit, a lifetime of an electrolytic capacitor having the shortest lifetime among circuit components used for the power supply unit is estimated as a lifetime of the power supply unit. It is known that the lifetime of the electrolytic capacitor can be calculated by the following arithmetic expression based on the Arrhenius law which is a law of temperature-lifetime showing a relation between a temperature and a lifetime:
Lx: estimated lifetime at the time of actual use (time) Lo: warranty lifetime (time) at a maximum using temperature To: maximum using temperature (° C.) tx: actual using temperature (° C.) k: lifetime coefficient Various equations for the lifetime coefficient k are proposed by capacitor makers, and the coefficient is a conversion coefficient obtained from applied voltage, ripple current, ambient temperature or the like. Various estimating methods of lifetime based on such arithmetic expressions are conventionally proposed. However, in the conventional technique, estimated lifetime is calculated using the arithmetic expression based on the Arrhenius law, actual operating time is subtracted from this estimated lifetime, and a result of this subtraction reaches a predetermined threshold value, it is judged that it is at the end of the lifetime, and an alarm is given. Therefore, the conventional technique can not inform a lifetime at the time of actual use. Generally, exchange of electronic equipment used for various production equipment is incorporated in an annual schedule so that producing operation is not interfered. Therefore, the conventional technique in which an alarm informing that the electronic equipment is at the end of the lifetime is output or indicated suddenly one day can not be used easily. If the alarm informing that the equipment is at the end of the lifetime is output or indicated on a day other than a periodical maintenance term, there is a problem that the line must be stopped for exchanging the equipment. Therefore, it is desired to estimate a remaining lifetime at the time of actual use, for example, to estimate remaining time during which the equipment can be operated. Further, in order to precisely estimate a lifetime based on the Arrhenius law, it is necessary to precisely detect an actual using temperature (tx) of an electrolytic capacitor as apparent from the above arithmetic expression. A temperature sensor is provided for detecting the actual using temperature of the electrolytic capacitor, but since the detection is affected by convection of ambient air, it is not easy to precisely detect the temperature. Especially in a power supply unit, a primary circuit and a secondary circuit are electrically insulated from each other by a transformer. The electrolytic capacitor whose lifetime is to be estimated is the primary circuit, but an arithmetic circuit such as a low-voltage operated microcomputer which calculates the lifetime based on a temperature detected by the temperature sensor is the secondary circuit. Therefore, it is more difficult to precisely detect a temperature of the electrolytic capacitor while keeping the insulation between the electrolytic capacitor and the temperature sensor. The present invention has been accomplished in view of such circumstances, and it is a main object of the present invention to estimate a remaining lifetime at the time of actual use, and it is an object of the invention to provide a temperature detecting structure suitable for enhancing the estimating precision, and an electronic equipment capable of informing the remaining lifetime. To achieve the above object, the present invention has the following structures. That is, an estimating method of a remaining lifetime of a subject according to the present invention comprises a calculating step for calculating a remaining lifetime at a predetermined temperature in accordance with an arithmetic expression based on a temperature-lifetime law, and a converting step for converting the calculated remaining lifetime into a remaining lifetime in actual use. According to the present invention, the remaining lifetime at the predetermined temperature is calculated in accordance with the arithmetic expression based on the temperature-lifetime law, and the result is converted into the remaining lifetime in actual use. Therefore, it is possible to estimate the remaining lifetime in actual use, and it is possible to grasp the exchanging time form this remaining lifetime, and to make a maintenance schedule. According to an embodiment of the present invention, the calculating step and the converting step are carried out whenever a predetermined time is elapsed, in the calculating step, the predetermined time elapse in actual use is converted into an elapsed time at the predetermined temperature, and the converted value is subtracted from the remaining lifetime, the converting step is carried out based on a proportional relation between the remaining lifetime at the predetermined temperature and the remaining lifetime in actual use. Here, “whenever a predetermined time is elapsed” means “whenever a constant time is elapsed”, for example, this may mean constant time intervals or non-constant time intervals. According to the present invention, if the predetermined time is elapsed, this elapsed time is converted into an elapsed time at the predetermined temperature, the converted value is subtracted from the remaining lifetime at the predetermined temperature, and the obtained remaining lifetime at the predetermined temperature is converted into the remaining lifetime in actual use using the proportional relation. Therefore, whenever the predetermined time is elapsed, it is possible to estimate the remaining lifetime at that time point. In another embodiment of the present invention, in the calculating step, the conversion is carried out based on the temperature-lifetime law using a temperature at the time of actual use, in the conversion step, the calculated remaining lifetime is converted into the remaining lifetime in actual use based on a remaining lifetime at another time point at the predetermined temperature and an elapsed time in actual use corresponding to the other time point while using a total remaining lifetime at the initial stage at the predetermined temperature as a reference. According to the present invention, if the predetermined time is elapsed, the elapsed time is converted into an elapsed time at the predetermined temperature based on the temperature-time law using the actual using temperature. Therefore, the conversion is carried out correctly even if the actual using temperature is changed from the predetermined temperature. Further, since the converted elapsed time is subtracted from the remaining lifetime at the predetermined temperature, the calculated remaining lifetime at the predetermined temperature is based on the past histories including the actual using temperature heretofore, and it is possible to precisely estimate the remaining lifetime. Further, since the conversion is carried out while using the initial total remaining lifetime at the predetermined temperature as the reference, it is possible to convert into the remaining lifetime in actual use precisely as compared with a case in which the remaining lifetime at a time point after the actual use is started is used as the reference. In another embodiment of the present invention, the estimated subject of the remaining lifetime is a capacitor. According to the present invention, since a remaining lifetime of the capacitor can be estimated, it is possible to estimate remaining lifetimes of various equipment having capacitors as a remaining lifetime of the capacitor. In a structure for detecting a temperature of a capacitor according to the present invention, an insulating tape is wound around a temperature sensor which detects a temperature of the capacitor to bring the temperature sensor into tight contact with the capacitor. According to the present invention, an extremely thin tape is commercially available as the insulating tape, even if such an insulating tape is wound, its thickness is extremely thin, it is possible to dispose the temperature sensor extremely close to the capacitor while ensuring a desired insulating performance, and it is possible to precisely detect a temperature of the capacitor. In another embodiment of the present invention, the temperature around which the insulating tape is wound and the capacitor are accommodated in a heat-shrinkable tube and are integrally formed together. According to the present invention, both the capacitor and the temperature sensor are integrally formed by the thermal shrinkage of the heat-shrinkable tube in a state in which both of them are in tight contact through the insulating tape, a temperature in the tube is equalized by heat conductivity of the heat-shrinkable tube, and a difference between the capacitor temperature and the temperature detected by the sensor is not generated almost at all. Thermal capacities become the same due to the integral formation, and a case in which a temperature of only the temperature sensor is abruptly varied due to outside air wind is not caused. In another embodiment of the present invention, the capacitor is a primary circuit component which is insulated by a transformer, the temperature sensor is a part incorporated in a secondary circuit, the temperature sensor is connected to the secondary circuit through a lead wire. According to the present invention, the desired insulation between the capacitor which is the primary circuit component and the temperature sensor incorporated in the secondary circuit can be ensured by winding the insulating tape. The temperature sensor which is disposed in tight contact with the capacitor must be connected to the secondary circuit, but since the temperature sensor is connected through the wiring pattern of the circuit substrate to which the primary circuit components including the capacitor are mounted, it is difficult to secure a distance necessary for insulation. Thereupon, using the lead wire, the wiring pattern spans the secondary the circuit substrate to the secondary circuit from above without laying on the circuit substrate, and the connection can be carried out while securing the desired insulating performance. An electronic equipment having a capacitor of the present invention comprises a temperature sensor for detecting a temperature of the capacitor, calculating means for calculating a remaining lifetime of the capacitor using a detected temperature from the temperature sensor, and informing means for informing of the calculated remaining lifetime, and the calculating means includes a calculating section for calculating a remaining lifetime at a predetermined temperature in accordance with an arithmetic expression based on a capacitor temperature-lifetime law. According to the present invention, the remaining lifetime at the predetermined temperature is calculated in accordance with the arithmetic expression based on the capacitor temperature-lifetime law using the detected temperature from the temperature sensor which detects the temperature of the capacitor. Since the remaining lifetime at the predetermined temperature and the remaining lifetime in actual use are proportional to each other, a ratio of the initial total remaining lifetime at the predetermined temperature to the remaining lifetime calculated in accordance with the arithmetic expression can be regarded as the ratio in actual use. It is possible to inform that what % the remaining lifetime occupies in the total lifetime (total remaining lifetime) for example, and based on this, it is possible to grasp the exchanging time and to make a maintenance schedule. In another embodiment of the present invention, the calculating means calculates a remaining lifetime of the capacitor in actual use, the calculating means includes a converting section for converting the remaining lifetime at the predetermined temperature calculated by the calculating section into the remaining lifetime in actual use, the informing means indicates the calculated remaining lifetime. According to the present invention, the remaining lifetime at the predetermined temperature is calculated in accordance with the arithmetic expression based on the capacitor temperature-lifetime law, and the result is converted into the remaining lifetime in actual use and the converted value is indicated. Therefore, it is possible to grasp the exchanging time from this remaining lifetime and to make a maintenance schedule. In another embodiment of the present invention, the calculating means calculates a remaining lifetime of the capacitor in actual use whenever a predetermined time is elapsed, the calculating section converts the predetermined time elapse in actual use into an elapsed time at the predetermined temperature and subtracts the converted value from the remaining lifetime, the converting section converts based on a proportional relation between the remaining lifetime at the predetermined temperature and the remaining lifetime in actual use. According to the present invention, if the predetermined time is elapsed, the elapsed time is converted into the elapsed time at the predetermined temperature, the converted value is subtracted from the remaining lifetime at the predetermined temperature, the obtained remaining lifetime at the predetermined temperature is converted into the remaining lifetime in actual use utilizing the proportional relation and the converted value is informed. Therefore, whenever the predetermined time is elapsed, a remaining lifetime at that time point can be informed. In a preferred embodiment of the present the calculating section carries out the conversion based on a capacitor temperature-lifetime law using a detected temperature from the temperature sensor, the conversion section converts the calculated remaining lifetime into the remaining lifetime in actual use based on a remaining lifetime at another time point at the predetermined temperature and an elapsed time in actual use corresponding to the other time point while using a total remaining lifetime at the initial stage at the predetermined temperature as a reference. According to the present invention, if the predetermined time is elapsed, the elapsed time is converted into an elapsed time at the predetermined temperature based on the capacitor temperature-lifetime law using the actual using temperature. Therefore, the conversion is carried out correctly even if the actual using temperature is changed from the predetermined temperature. Further, since the converted elapsed time is subtracted from the remaining lifetime at the predetermined temperature, the calculated remaining lifetime at the predetermined temperature is based on the past histories including the actual using temperature heretofore, and it is possible to precisely estimate the remaining lifetime. Further, since the conversion is carried out while using the initial total remaining lifetime at the predetermined temperature as the reference, it is possible to convert into the remaining lifetime in actual use precisely as compared with a case in which the remaining lifetime at a time point after the actual use is started is used as the reference. In another embodiment of the present invention, the electronic equipment further comprises means for replacing the initial total remaining lifetime which is a reference of conversion in the converting section by a remaining lifetime at another time point. According to the present invention, when the electronic equipment is used in an environment in which the temperature condition is largely changed, by replacing the conversion reference point by a time point after the temperature condition is changed, it is possible to precisely calculate the remaining lifetime. In another embodiment of the present invention, the capacitor is a primary circuit component which is insulated by a transformer, the temperature sensor is a part incorporated in a secondary circuit, an insulating tape is wound around the temperature sensor, and the temperature sensor is brought into tight contact with the present capacitor. According to the present invention, an extremely thin tape is commercially available as the insulating tape, even if such an insulating tape is wound, its thickness is extremely thin, it is possible to dispose the temperature sensor extremely close to the capacitor while ensuring a desired insulating performance between the primary capacitor and the secondary temperature sensor, and it is possible to precisely detect a temperature of the capacitor. In another embodiment of the present invention, the temperature around which the insulating tape is wound and the capacitor are accommodated in a heat-shrinkable tube and are integrally formed together, the temperature sensor is connected to the calculating means through a lead wire. According to the present invention, both the capacitor and the temperature sensor are integrally formed by the thermal shrinkage of the heat-shrinkable tube in a state in which both of them are in tight contact through the insulating tape, a temperature in the tube is equalized by heat conductivity of the heat-shrinkable tube, and a difference between the capacitor temperature and the temperature detected by the sensor is not generated almost at all. Thermal capacities become the same due to the integral formation, and a case in which a temperature of only the temperature sensor is abruptly varied due to outside air wind is not caused. The temperature sensor which is disposed in tight contact with the capacitor is connected to the secondary circuit, but since the temperature sensor is connected through the wiring pattern of the circuit substrate to which the primary circuit components including the capacitor are mounted, it is difficult to secure a distance necessary for insulation. Thereupon, using the lead wire, the wiring pattern spans the secondary the circuit substrate to the secondary circuit from above without laying on the circuit substrate, and the connection can be carried out while securing the desired insulating performance. In a preferable embodiment of the present invention, the informing means can switch indication manners of the calculated remaining lifetime between character indication and numerical value indication. According to the present invention, when a time period during which the lifetime is elapsed is excessively long, if the time period is indicated with characters, it is possible to roughly grasp the deterioration degree. If the time period during which the lifetime is elapsed is shortened, the indication manner is switched to the numerical value indication so that the indication can effectively be utilized for management. In another embodiment of the present invention, the calculating means includes a deterioration degree calculating section for calculating a rate of the remaining lifetime at the predetermined temperature calculated by the calculating section to the initial total remaining lifetime at the predetermined temperature, the informing means indicate the calculated deterioration degree. According to the present invention, the indication manner of the calculated remaining lifetime is not limited to the numerical value indication on the basis of years, months, or hours, and it is possible to indicate that what percent the electronic equipment is used and deteriorated in the total lifetime (total remaining lifetime), and it is possible to manage the exchanging time based on the deterioration degree. An embodiment of the present invention will be explained below based on the drawings. This power supply unit A shallow box-like resin auxiliary case The power supply circuit unit The arithmetic circuit unit According to the above structure, the front cover The power supply circuit unit This embodiment includes an output voltage detecting circuit In this embodiment, in order to make it possible to grasp the exchanging time of the power supply unit In order to calculate the lifetime of the electrolytic capacitor In this case, the electrolytic capacitor Thereupon, in this embodiment, the following temperature detecting structure is proposed. That is, as shown in Further, the temperature sensor By insulating and coating the temperature sensor The electrolytic capacitor A thickness and a width of the thin film tape Further, in this embodiment, a lead wire Next, a calculating method of a remaining lifetime of the electrolytic capacitor It is known that the lifetime of the electrolytic capacitor can be calculated by the following arithmetic expression based on the Arrhenius law as described above:
Lx: estimated lifetime at the time of actual use (time) Lo: warranty lifetime (time) at a maximum using temperature To: maximum using temperature (° C.) tx: actual using temperature (° C.) k: lifetime coefficient In this embodiment, a temperature t That is, L Next, when the actual use of the power supply unit As shown in this equation (2), the remaining lifetime L In this equation (2), the second term of the right side, for example, a×2 Every constant time a, the constant time a is converted into the elapsed time at the predetermined temperature to based on the Arrhenius law using the actual using temperature tx detected during the constant time, and the converted value is subtracted from the last remaining lifetime L Therefore, the remaining lifetime L The remaining lifetime L As described above, whenever the constant time a is elapsed, the remaining lifetime L In this embodiment, utilizing a fact that a remaining lifetime at the predetermined temperature t Therefore, a remaining lifetime Lrest at said certain time point n can be calculated by the following equation:
That is, the remaining lifetime Lrest in the actual use is calculated from the total remaining lifetime L However, since there is an adverse possibility that the inclination of the straight line is largely varied at the initial stage of the start of operation, if the Xx becomes equal to or greater than a predetermined Xmax (Xx≧Xmax), Xx is set to Xmax. The remaining lifetime Lrest in the actual use calculated in this manner may be indicated with numerical values on the basis of years, months, days or hours, but a lifetime of an electrolytic capacitor is generally from several years to a dozen years. Therefore, if the remaining lifetime Lrest is indicated with numerical values from the initial stage of start of operation, since there is too much time until the electrolytic capacitor comes to its end of remaining lifetime, this is not effectively,used. Further, since the variation in inclination of the above straight line is increased as the elapsed time Xn from the start of operation is shorter, the variation in the calculated remaining lifetime Lrest in actual use is also increased. Thereupon, in this embodiment, the calculate remaining lifetime Lrest in the actual use is indicated in the following manner: That is, Since a lifetime of an electrolytic capacitor is determined as being elapsed when its initial lifetime is reduced by 20 to 30%. Therefore, after the calculated remaining lifetime Lrest in the actual use becomes equal to or lower than a constant value (two years in this example), the lifetime is indicated with numerical values, a time period required from the initial value to the instant when the indication manner is changed to the year-base indication of numerical values is equally divided and indicated on the LED indicator In this embodiment, when the using conditions such as a temperature and a load are largely varied due to change of equipment or the like and the inclination of the straight line in A remaining lifetime Lrest in the actual use at a C time point (X The above-described equation (3) is calculated while defining a point of a total remaining lifetime L On the other hand, at C time point (X Thereupon, in this embodiment, when the using conditions such as a temperature and a load are largely varied due to change of equipment or the like, reset is carried out by a switch or an external signal at that time point, the reference point is replaced and a remaining lifetime having no error is indicated. In this embodiment, it is also possible to calculate how much the present lifetime is reduced as compared with the total remaining lifetime L Since the inclination of the straight line shown in Another Embodiment In the previous embodiment, the remaining lifetime is calculated every predetermined constant time. As the other embodiment of the present invention, the remaining lifetime may be calculated and indicated in response to the operation. Although the point of intersection between the lateral axis and the straight line connecting two points is defined as the elapsed time Xx in the above embodiment, the straight line is not limited to one connecting the two points, and the straight line may be obtained by a method of least squares using three or more points. According to the present invention as explained above, a remaining lifetime at a predetermined temperature is calculated in accordance with the arithmetic expression based on the temperature-lifetime law, the remaining lifetime is converted into a remaining lifetime in the actual use and is informed. Therefore, it is possible to grasp the exchanging time from this remaining lifetime and to make a maintenance schedule. Thus, a case in which the equipment suddenly comes to the end of its remaining lifetime and the line of the equipment is stopped can be avoided unlike the conventional technique which informs of the end of lifetime. This is especially effective to grasp the exchanging time of various electronic equipment such as a power supply unit having a capacitor. Further, according to the invention, a thin insulating tape is round around a temperature sensor, the temperature sensor can be disposed in close contact with the capacitor while ensuring the insulation, and a temperature can be detected precisely. Since the temperature sensor and the electrolytic capacitor are integrally formed together using a heat-shrinkable tube, a case in which a temperature of only the temperature sensor is abruptly varied due to outside air wind is not caused, and it is possible to precisely detect a temperature and thus it is possible to precisely calculate a remaining lifetime. Patent Citations
Non-Patent Citations
Referenced by
Classifications
Legal Events
Rotate |